Roller for a winding machine

ABSTRACT

Webs of paper or cardboard are rolled up using carrying or supporting rollers or pressing rollers with a hollow cylindrical body of a rigid material to which a deformable layer is applied. The deformable layer consists of a cellular plastic material partly with open pores and partly with pores which are closed on themselves and in which the pore size can be less than 5 mm. The compression modulus of the material is less than 10 MPa.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage of PCT/EP97/00146, filed Jan. 15,1997 and based on German National Application 196 032 11.3 of Jan. 30,1996 and 296 15 385.0 of Sep. 4, 1996 under the InternationalConvention.

TECHNICAL FIELD

The invention relates to a roller for a winding machine, particularlyfor winding paper or cardboard webs, whose purpose it is to be pressedagainst the winding rolls during winding and to a winding machineprovided with a roller according to the invention.

STATE OF THE ART

In order to produce wound-up rolls from longitudinally subdivided paperor cardboard webs, it is known to use winding machines with one or twodriven rollers against which the winding rolls rest or on which they aresupported. The rollers are known as support rollers when they bear thefull weight of the supported winding roll (DE-A 39 24 612). When theweight is totally or only partially supported by guide heads inserted inthe sleeves of the winding roll and held on support arms, then theroller is defined as a backing roller (DE-C 31 02 894, DE-C 40 12 979).

Furthermore winding machines comprise a so-called pressure roller, whichat the onset of winding is pressed in opposite direction to the contactline between the winding roll and a support or backing roller, when thecontact pressure resulting from the weight of the roll is not yetsufficient to obtain the desired winding firmness and which contributesconsiderably to the stability of the winding operation (DE-C 37 19 093,EP-C0410093).

The winding firmness which is decisive for the quality of the woundrolls (surface compression between the layers of a wound roll) dependson the line load and the geometric conditions in the nip between thewinding roll and the support or backing roller. The term "line load"means the contact pressure scaled to the width of the winding roll andmeasured in N/m. In the production of wound rolls all efforts are aimedat setting a predetermined, uniform winding firmness at high speeds,without surface damage or winding defects occurring in the wound roll.Winding defects are caused by excessive stretching of the web in thenip. Since the stretching in the nip between the support roller and awinding roll increases with the increasing diameter of the roll, itsvalue limits the maximal final diameter of a wound roll free of windingdefects.

In order to produce good-quality wound rolls with a larger diameter, theEP-A-0562266 proposes a winding machine with support rollers whosesupport roller on the outgoing side, which is not wrapped by the web andis lower with respect to the support lower roller on the incoming side,is provided with shell which is considerably more deformable than theshell of the support roller on the incoming side. According to oneembodiment the support roller has an outer layer of rubber, whereinchambers connected to the steel interior of the support body areprovided. Due to the strong deformability, the contact pressure on thesupport roller should be as limited as possible, so that the windinghardness does not increase disproportionally.

OBJECT OF THE INVENTION

It is the object of the invention to create a roller for a windingmachine, which when used as a support or backing roller will makepossible a winding with a lower winding hardness. When used as apressure roller, it should be capable to compensate the variations inthe uniformity of the winding rolls, e.g. the ones resulting from theweb profile variations, and to insure this way the uniformity of thecontact pressure.

This object is achieved, in accordance with the invention in a rollerfor a winding machine for winding paper or cardboard webs into rolls andwhich comprises a hollow cylindrical support body made of a rigidmaterial and a deformable layer on a peripheral surface of the body. Thedeformable layer consists of a cellular plastic material with amultitude of uniformly distributed pores and of a compression modulus kof less than 10 MPa.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become morereadily apparent from the following description, reference being made tothe accompanying drawing in which:

FIG. 1 is a longitudinal section through a support of the backing rollerof the invention;

FIG. 2 is a cross section through the roller of FIG. 1,

FIGS. 3 to 5 are enlarged sections of various configurations of theouter shell layer of the roller;

FIG. 6 is a section of a roller wherein the compressible layer consistsof individually applied rings, and

FIGS. 7 and 8 are diagrams of the way a support roller of the inventionworks within a winding machine with support rollers, in comparison to asupport roller according to the state of the art.

WAY TO IMPLEMENT THE INVENTION

FIG. 8 illustrates the principle of a winding machine with supportrollers for producing wound rolls 2 from longitudinally subdivided paperor cardboard webs 1, wherein the roller shown in FIGS. 1 to 6 is used asa support roller or as a pressure roller. A winding machine with supportrollers comprises two driven support rollers 3, 4 on which duringwinding the winding rolls 2 are supported coaxially and aligned andwhich therefore bear the entire weight of the winding rolls. Preferablythe paper or cardboard web 1 is guided from below through the gapbetween the support rollers 3, 4 partially wrapping the support roller 4on the incoming side and feeding into the nip between the support roller4 on the incoming side and the winding roll 2 resting on the latter.

One or both support rollers 3, 4 of the winding machine with supportrollers are equipped as the rollers of the invention. Preferably theroller according to the invention is used as a support roller 3 on theoutgoing side, which with respect to the support roller 4 on theincoming side is arranged so that its contact line to the winding roll(nip 5) is at the same level or lower than the contact line between theother support roller 4 and the winding roll. In this way the supportroller 3 bears the same or a greater portion of the weight of thewinding roll 2. In addition it is also possible to equip the supportroller 4 on the incoming side as a roller according to the invention.

On top of the winding rolls 2 rests a pressure roller 6 extending overthe entire work width of the winding machine, i.e. the axial length ofthe support rollers 3, 4, which at the onset of the winding processpresses the winding rolls 2 against the support roller 3, 4, when theweight of the winding rolls is not yet sufficient for the desiredwinding hardness.

In FIGS. 1 to 6 the construction of the roller according to theinvention used either as a support or a backing roller is described indetail. As a support or backing roller 3 it has an axial length whichcorresponds to the maximal width of the paper or cardboard web 1 to beprocessed, which can amount up to 10 m. Its diameter ranges between 500mm and 1500 mm. The support or backing roller of the invention consistsof a hollow cylindrical support body 7 made of a rigid material,particularly steel, with a sufficiently stable design, so that it canwithstand the forces acting upon the winding rolls 2 supported thereonor resting thereagainst and prevent them from bending. On both ends ofthe support body 7 pivots 8 are provided, by means of which the roller 3is mounted in the frame of the winding machine. One of the pivots 8 ofeach support or backing roller 3 is connected to a rotary drive, bymeans of which the roller 3 is turned about its longitudinal axis, inorder to rotate the winding rolls 2 for the purpose of winding.

On the outer peripheral surface of the support body 7 a layer 9 isapplied, made of a cellular plastic material, with a multitude of poresfilled with a gas, particularly air, which makes it compressible andwhich has a compression module k of less than 10 MPa. It is importantthat a great number of relatively small pores be evenly distributed overthe volume of the layer 9. Preferably the pore size is less than 5 mm, apore size between 0.05 mm and 1 mm has proven to be advantageous.Preferably the pores in the layer 9 are partially open--which means thatthey are interconnected--, and partially they are closed. The proportionof the open pores amounts to 30% to 70%, preferably approximately 50%.The ratio between the open pores and the closed pores determines thecompressibility, as well as the capability of the layer to carry off theheat produced within it, in order to avoid undesirable overheating.

Advantageously for the layer 9 a cellular elastomer produced by foaming,particularly polyurethane is used, with a compression module k of 1 MPato 5 MPa. The radially measured thickness of the layer 9 amounts to atleast 10 mm, preferably between 10 mm and 40 mm, in the exampleapproximately 25 mm. The density of the material of layer 9 with thepores amounts to less than 800 kg/m³, preferably between 350 to 650kg/m³. According to a preferred embodiment the layer 9 has a hardnessranging between 15 and 60 Shore-A. Therefore the roller is relativelysoft on its outer surface, in order to form a wider nip at contact witha winding roll.

FIGS. 3 to 5 show various possibilities of mounting the compressiblelayer 9 on the support body 7.

In the embodiment of FIG. 3 the peripheral surface of the support body 7is provided exclusively with a layer 9 of compressible material,preferably a cellular elastomer. The thickness of the layer 9 rangesbetween 10 mm and 40 mm.

A multitude of circular and spaced apart grooves not shown in FIG. 3 areworked into the outer surface of the layer 9, in order to avoid thewinding in of air into a winding roll 2 or to reduce an excessive noisedevelopment during winding.

In the embodiment according to FIG. 4, between the compressible layer 9and the support body 7, a hard ground layer 10 is provided, made ofincompressible material, preferably rubber, which is skidlesslyconnected with the support body 7. The nonskid connection can beachieved for instance through vulcanization. In order to form awear-resistant outer tread surface 11, on the outside of thecompressible layer 9 a further elastic layer is provided, which can begrooved, if required.

FIG. 5 shows an embodiment with surrounding grooves 12 in awear-resistant outer layer 11. The compressible layer 9 is directlyfastened to the support body 7 without an intermediate layer.

In the embodiments according to FIGS. 4 and 5 with an additional elasticbut incompressible layer 11 it is important that its construction andcharacteristics are selected so that, as a purely protective layer itdoes not seriously influence the deformability, especially thecompressibility of the peripheral surface of the support or backingroller 3 under the weight of a winding roll 2. In order to diminish itsinfluence on the deformability, the outer tread surface 11 can beweakened by cuts running across the grooves 12.

FIG. 6 shows the preferred embodiment of a support or backing roller ofthe invention, wherein the compressible layer 9 consists of individualrings 13. The rings 13 having a width of 50 mm to 500 mm in the axialdirection of the roller are arranged either in immediate succession orat such a short distance from each other that the gap between two rings13 cannot produce marks on the winding roll 2. If there is a distancebetween the rings 13, then it preferably ranges between 5 mm to 30 mm.Preferably rings 13 are used with an inner diameter which is larger thenthe desired thickness of the layer 9 and somewhat smaller than the outerdiameter of the support body 7. One after the other the rings 13 arepushed with a stretched inner diameter over the support body 7 so thatafterwards they are lodged on the support body 7 under tension. Thetension insures a slip-free fit of the rings 13 on the support body 7. Asufficiently firm fit can also be achieved when the rings 13 arefastened to the support body 7 by positive locking, or through cementingor jamming. The rings 13 are arranged parallel to each other on thesupport body 7, so that their frontal surfaces run eitherperpendicularly or obliquely with respect to the roller axis. In thesecond variant the rings form a quasi-screw thread with the advantagethat the gap between the rings 13 permanently varies its position duringrotation, this way avoiding marks on an adjacent winding roll.

Another possibility to mount the compressible layer 9 on the supportroller 7 consists in winding a compressible strip material onto thesupport body 7 in the form of a screw thread. The slip-free fit of thelayer 9 can be achieved with the aforedescribed techniques, by windingthe strip in a prestressed state. The roller consists then of a supportbody 7 with a compressible layer 9 made of a strip-like material woundin the manner of a screw thread.

The advantageous influence of a support or backing roller 3 compared tothe known support or backing rollers 14 with an elastic butincompressible peripheral surface (e.g. made of solid rubber) isexplained in FIGS. 7 and 8.

FIG. 7 shows a winding machine with support rollers according to thestate of the art, wherein the support roller 14 on the outgoing side hasan elastic but incompressible peripheral surface. Under the weight ofthe winding roll 2 the support roller 14 is elastically deformed in thenip 5. The yielding elastic material forms on both ends of nip 5 theswellings 15, which protrude radially with respect to the rest of theperipheral surface. The swellings 15 on the nip 5, which evidentlyinfluences the winding hardness, increase the effective radius of thesupport roller 14, so that the outermost layer of the winding roll 2 isaccelerated. This acceleration increases the so-called nip-inducedstretching of the outer layer, i.e. the winding hardness increases. Thepositive effect intended by the outer elastic layer, namely to reducethe contact pressure and thereby also the winding hardness depending onthe contact pressure through the widening of the nip 5, is decisivelydiminished and can even be reversed to the contrary.

FIG. 8 represents the conditions during winding with a winding machinewith support rollers when a support roller 3 according to the inventionis used.

Under the weight of the winding roll 2 the compressible layer 9 iscompressed, its volume is reduced. A wider nip 5 with no swellings orwith negligibly small swellings at both ends results. The contactpressure on the support roller 3 decreases as a result of the wider nip5 and the nip-induced stretching of the outermost layer on the windingroll 2 is reduced. Compared to the known winding machines, it ispossible to wind with reduced winding hardness at the same contactweight per meter of roller length. This allows for the winding of rollswith a bigger final diameter, without damaging the paper or cardboardweb or without producing defects in the wound roll 2.

The use of a roller according to the invention is not limited to use asa support roller in winding machines with support rollers, but it canalso be advantageously used in other types of winding machines, as acontact roller pressed against the winding rolls, in order to producelarge-diameter and high-quality wound rolls at high production speeds.It is particularly advantageous to use it as a support roller inso-called support-roller winding machines wherein on both sides of acentral support roller winding stations are arranged in two windinglines and which are alternately fed with the individual webs. Eachwinding roll--as for instance described in German Patent 36 29 024--isheld by two guide heads supported on winding brackets of the windingstation, which take up a part of the weight of the winding rolls. Theremaining part is taken up by the central support roller on which thewinding roll is supported.

When used as a pressure roller, which is marked with the referencenumeral 6 in FIGS. 7 and 8, in the case of small axial length the rolleris built as previously described in FIGS. 1 to 6. Since pressure rollersare supported freely rotatable and are not driven, no rotary driveengages at the pivot 8. In pressure rollers with large axial length,such as used for instance in support-rollers winding machines, thepressure roller is preferably made of segments which are individuallyrotatably supported, in order to make possible an independent rotationof each segment. Pressure rollers have diameters ranging between 200 to400 mm, i.e. normally smaller diameters than the support or backingrollers.

We claim:
 1. A roller for a winding machine for winding paper orcardboard webs into rolls, said roller comprising:a hollow cylindricalsupport body made of a rigid material; and a deformable layer on saidbody and consisting of cellular plastic material with a multitude ofuniformly distributed pores and of a compression modulus k of less than10 MPa, said pores being partially open pores and partially pores closedoff on themselves.
 2. The roller defined in claim 1 wherein the layerconsists of a cellular elastomer particularly polyurethane, with acompression modulus between 1 MPa and 5 MPa.
 3. The roller defined inclaim 2 wherein the layer consists of polyurethane.
 4. The rollerdefined in claim 1 wherein the size of the pores is less than 5 mm. 5.The roller defined in claim 4 wherein the size of the pores is between0.05 mm and 1 mm.
 6. The roller defined in claim 1 wherein theproportion of open pores is 30% to 70%.
 7. The roller defined in claim 6wherein the proportion of open pores is about 50%.
 8. The roller definedin claim 6 wherein the layer has a hardness of between 15 and 60 ShoreA.
 9. The roller defined in claim 6 wherein the thickness of the layeris at least 10 mm.
 10. The roller defined in claim 9 wherein thethickness of the layer is between 10 mm and 40 mm.
 11. The rollerdefined in claim 9 wherein a wear-resistant elastic running layer isapplied to an outside of the deformable layer.
 12. The roller defined inclaim 11 wherein the elastic running layer has grooves.
 13. The rollerdefined in claim 1 wherein between the deformable layer and the supportbody is arranged a hard base layer which consists of an incompressiblematerial and which is connected to the support body in a non-slipmanner.
 14. The roller defined in claim 1 wherein the deformable layeris composed of individual rings.
 15. The roller defined in claim 14wherein the rings are arranged at a distance of 5 mm to 50 mm from oneanother.
 16. The roller defined in claim 14 wherein end faces of therings run obliquely to a roller axis.
 17. The roller defined in claim 1wherein the deformable layer consists of a helically applied tape-likematerial.
 18. A winding machine for winding paper or cardboard webs intorolls, comprising at least one supporting or pressing roller, saidroller comprising:a hollow cylindrical support body made of a rigidmaterial; and a deformable layer on said body and consisting of cellularplastic material with a multitude of uniformly distributed pores and ofa compression modulus k of less than 10 MPa, said pores being partiallyopen pores and partially pores closed off on themselves.
 19. The windingmachine according to claim 18 with two supporting rollers carrying theweight of the winding roll, with one of the two carrying rollers beingarranged in such a way that a line of contact with the rolls is lowerthan the line of contact of the other supporting roller, at least thesupporting roller with the lower line of contact having said layer.